Volume 2 Issue 2
Effect of some root associative bacteria on germination of seeds, nitrogenase
activity and dry matter production by rice plants
Author(s): A. C. DAS AND S. C. KOLE
Abstract: An experiment was conducted under laboratory conditions with five efficient strains of root associative bacteria of
which two N2-fixing bacteria viz. Azotobacter sp. (strain AS2) and Azospirillum sp. (strain AM3), one phosphate
solubilizing Bacillus sp. (strain BP3), one sulphur oxidizing Thiobacillus sp. (strain BT1) and one sulphur
mineralizing Bacillus sp. (BC5) isolated from the root surface of rice (Oryza sativa L. cv. IR-36) to investigate the
effect of combined inoculation of the non-diazotrophic root associative bacteria (BP3, BT1 and BC5) in presence of
N2-fixing bacteria on the rate of germination of rice seeds, nitrogenase activity (C2H2 reduction) of the roots and dry
matter accumulation of the rice seedlings grown in a synthetic medium for 30 days. Inoculation of non-diazotrophic
root associative bacteria in combination with N2-fixing bacteria significantly stimulated the rate of germination of
seeds as well as the nitrogenase activity of the microbes present in the roots and dry matter accumulation of rice
seedlings. After 10 days of inoculation, the maximum seed germination (96.3%) was recorded with the combined
inoculation of AS2, AM3, BP3 and BT1. This was followed by the combined inoculation of AS2, BP3, BT1 (92.7%);
AS2, BP3, BT1, BC5 (92.3%); AS2, BT1 (90.7%); AM3, BP3, BT1 and BC5 (90.3%), respectively. Nitrogenase
activity of roots and dry matter production of the 30 day old seedlings were increased concurrently and the effects
were more pronounced with the combined inoculations of AS2, AM3, BP3, BT1 followed by AS2, BP3, BT1; AS2,
BP3, BT1, BC5 and AM3, BP3, BT1, BC5.
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